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The use of Tectona grandis leaf extract as a green corrosion inhibitor for stainless steel 304 (SS304) in 2 m hydrochloric acid was investigated using electrochemical techniques. Potentiodynamic polarization studies with different inhibitor concentrations showed that the inhibitor is of mixed type, which works by affecting both cathodic and anodic reactions. Adsorption analysis using the potentiodynamic polarization and electrochemical impedance spectroscopy runs result in standard free energy of adsorption values between −20 kJ mol−1 and −40 kJ mol−1, indicating a comprehensive adsorption, which is a mixture of both physisorption and chemisorptions processes. Fourier transform infrared spectroscopy studies show the appearance of new peaks and shift in peak positions at some locations with the use of an inhibitor, which indicates the interaction between the inhibitor molecules and metal surface. Contact angle analysis indicates the formation of hydrophobic film on the metal surface.

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Single-step ultrasound-assisted synthesis of Copper Zinc Tin Sulfide nanoparticles (CZTS) has been studied at two different frequencies. While the effects of frequency on the particle size of the CZTS nanoparticles were insignificant, a noticeable change was observed in composition. As-obtained particles presented the amorphous nature and spherical morphology with a high degree of agglomeration. Annealing of the synthesized CZTS nanoparticles increased the crystallinity while the sulfur content decreased considerably. The poly-dispersity and agglomeration of the nanoparticles increased upon annealing. The as-obtained CZTS nanoparticles synthesized at 45 kHz frequency presented a copper deprived and zinc-rich composition suitable for higher photo-conversion efficiency of the solar cells. The bandgap of the annealed and non-annealed particles ranged between 1.25 eV and 1.65 eV.